The basic criticism leveled against the price system concerned its tendency to undermine the government's drive for economic efficiency through the failure of prices to reflect production costs, improper relationships among prices, and price inflexibility. A comprehensive, unified approach to price reform was considered beyond the capability of the authorities; a piecemeal approach of dealing separately with different types of prices was therefore decided upon. Priority in this program was given to the improvement of industrial wholesale prices. Wholesale prices for industrial products have been based on average costs for each product in the relevant industrial branch. Prices have therefore been profitable for enterprises having below-average costs, whereas enterprises with costs above the average have had to rely upon state subsidies for continued operation. Wholesale prices were last fixed in 1963, and subsequent changes in technology and other aspects of production magnified the dissociation of prices and costs. For political reasons and because of general shortages the closing of uneconomic enterprises was not considered feasible. Maintenance of fixed prices over long periods of time has been deemed essential for purposes of planning. Under the prevailing price system, which assured high profits to many enterprises and provided subsidies for unprofitable ones, there was no incentive for enterprises to reduce costs. This tendency was reinforced by the methods used to calculate costs and prices. The fact that cost calculations did not include any charges for rent or capital induced waste in the use of land and equipment. Prices included an element of planned profit determined as a percentage of cost. In the price-setting procedure it was therefore advantageous for enterprises to overstate actual costs. This practice has been widely prevalent in fixing prices for new products. Prices for raw materials, including products of the extractive industries and agriculture, were generally set below the cost of production. This policy has been responsible for a wasteful use of many materials in manufacturing. A price discrepancy also served to negate the official fuel policy. Efforts to increase the use of coal in electric power production were frustrated by the relatively much lower price for natural gas. This led some economists to advocate that prices for fuels be based on their caloric content. The price system has also been reported to have produced various other inimical results, such as inhibiting innovation and rewarding the continued production of obsolete goods.